The purpose of this research is to develop an appropriate instrumentation system and associated data analysis techniques for evaluating the in-vivo mechanical properties of the brachial artery. Of particular interest is arterial distensibility, which can be evaluated in several ways. The most straightforward technique involves simultaneous measurement of arterial pressure and vessel diameter. An indirect and qualitative approach is also possible by analysis of the velocity waveform, a technique which can be performed non-invasively. Additionally, there are several theoretical formulations for arterial distensibility. Work on this project will be directed towards evaluating these various techniques to determine the limitations and advantages of each and to develop an instrumentation system suitable for routine clinical assessment of arterial mechanical properties.